1. Technical Field of the Invention
The present invention relates to an image recording system for recording information such as an image, a text, or the like, on a recording medium and in particular to an image recording system for recording the above information using K(black), C(cyan), M(magenta), and Y(yellow) color of toners on the recording medium.
2. Description of the Related Art
An image recording system incorporating the present invention has the following configuration:
(1) An optical head which has a plurality of laser beams, modulates the laser beams on/off as record data, and can be moved in a one-dimensional direction;
(2) a rotatable recording drum on which a recording material is placed;
(3) a recording medium made up of an image receiving sheet and K, C, M, and Y color toner sheets (pastel color toner sheets of gold, silver, brown, gray, etc., called special colors may be used) where laser beam transfer is enabled;
(4) a squeezing step of bringing the image receiving sheet and each color toner sheet into intimate contact with each other before recording of each color (further, a heating or pressurizing step may be executed);
(5) a step of peeling the toner sheet from the image receiving sheet after recording of each color; and
(6) a step of transferring four color (K, C, M, and Y) images transferred to the image receiving sheet to recording paper.
(6) may be executed by another machine.
A first problem concerns setting of recording speed. In a conventional image recording system, the recording speed for each of K, C, M, and Y colors is set to a constant value. Thus, for example, solid pixels, discoloration caused by abnormal transfer of a photo-heat conversion layer, a bridge of isolated pixels, halftone dot toner jump, etc., occurs or whole density increases on a highly sensitive toner sheet like K. On the other hand, on a toner sheet having poor sensitivity, thin pixels or lost halftone dots occur or whole density decreases, enough recording energy cannot be provided, and recording as image data cannot be accomplished.
A second problem is the relationship between recording speed and recording start position to record information with toner sheets of different colors. To rotate a recording drum and move an optical head, normally (1) a spiral system wherein the optical head moves continuously at predetermined speed in proportion to the drum rotation speed for recording or (2) an intermittent system wherein the optical head moves by predetermined step distance with one revolution of the drum is adopted. Therefore, if the drum rotation speed is changed, the optical head moving speed and the moving step time also change. To detect an origin point with respect to a moving direction of the optical head, for example, when the optical head moves toward a direction that a recording start point exists after the recording termination of the preceding color, the position at which the optical head passes through a position sensor such as a photo interrupter in the vicinity of the recording start point is recognized as the origin point.
To use toner sheets of different colors to record information, the recording sensitivity varies from one color to another. Thus, if the recording speed is changed in accordance with the toner sheet sensitivity, moving speed of the optical head changes. Resultantly, the speed at which the optical head passes through the origin point sensor also changes. However, since the sensitivity time of the sensor, defined as time between the sensor reacting and outputting a signal, is constant, accurate position information of the optical head cannot be provided due to difference of the moving distance of the optical head during the sensitivity time of the sensor. Since the result as record image data is not produced on an image receiving sheet because of the start position shift caused by changing the recording speed, image defects of registration difference, a color shift, moire, or the like, occur.
A third problem is setting of squeezing speed. A color proof printer requiring high definition and high quality uses toner sheets of different colors. A contactability with an image receiving sheet varies from one toner sheet to another. However, in the conventional image recording system, setting of the squeezing speed is limited to a constant value. Therefore, solid pixels, fog in a non-image area, a bridge of isolated pixels, inverse transfer of an image receiving layer, etc., occurs or whole density increases on a highly sensitive toner sheet. On the other hand, on a toner sheet having poor sensitivity, image unevenness, thin pixels, or lost halftone dots occur or whole density decreases and recording as image data cannot be accomplished.
A fourth problem is setting of squeezing pressure of a squeezing roller. A color proof printer requiring high definition and high quality uses toner sheets of different colors. The contactability with an image receiving sheet varies from one toner sheet to another. However, in the conventional image recording system, setting of the squeezing roller press pressure at the time of squeezing is limited to a constant value. Therefore, solid pixels, fog in a non-image area, a bridge of isolated pixels, inverse transfer of an image receiving layer, etc., occurs or whole density increases on a highly sensitive toner sheet. On the other hand, on a toner sheet having poor sensitivity, image unevenness or thin pixels occur or whole density decreases and recording as image data cannot be accomplished.
A fifth problem is setting of squeezing roller temperature at the squeezing time. A color proof printer requiring high definition and high quality uses toner sheets of different colors. The contactability with an image receiving sheet varies from one toner sheet to another. However, in the conventional image recording system, setting of the squeezing roller temperature at the squeezing time is limited to a constant value. Therefore, solid pixels, fog in a non-image area, a bridge of isolated pixels, inverse transfer of an image receiving layer, etc., occurs or whole density increases on a highly sensitive toner sheet. On the other hand, on a toner sheet having poor sensitivity, image unevenness, thin pixels, or lost halftone dots occur or whole density decreases and recording as image data cannot be accomplished.
It is therefore an object of the present invention to provide an image recording system which enables color reproduction as image output setting by changing recording process conditions for each color even if the characteristics of C, M, Y, and K color toners used for color print vary delicately.
To achieve the above object, there is provided an image recording system comprising: a rotatable recording drum on which an image receiving sheet and plural kinds of image recording mediums are mounted; an optical head for recording image information by exposing a laser beam to the image recording mediums while moving in one-dimensional direction at a speed in proportion to the rotation speed of the recording drum; a characteristics input section in which characteristics of the image recording medium is previously inputted; a conversion table storage section in which there is previously stored a conversion table converting the characteristics of the image recording mediums into setup values of parameters with respect to the image recording; and a parameter control section changing the setup values of the parameters based on the conversion table stored in the conversion table storage section in accordance with the kind of the image recording medium.
In the system, the parameter control section includes a recording drum rotation speed control section controlling the rotation speed of the recording drum based on the conversion table in accordance with the kind of the image recording medium.
The system further comprises a position sensor detecting the position of the optical head, and a position correction section correcting a position error deriving from a characteristic of the position sensor, wherein the characteristic of the position sensor is previously inputted in the characteristics input section, and wherein the position correction calculates and corrects the position error based on the characteristic of the position sensor inputted in the characteristics input section and the moving speed of the optical head obtained from the recording drum rotation speed control section.
The system further comprises a rotatable squeezing member abutting against the recording drum for providing squeezing pressure to bring the image recording mediums into adhesive contact with the image receiving sheet, wherein the parameter control section includes a squeezing member rotation speed control section controlling the rotation speed of the squeezing member based on the conversion table in accordance with the kind of the image recording medium.
In the system, the parameter control section includes a squeezing pressure control section controlling the squeezing pressure of the squeezing member with respect to the recording drum based on the conversion table in accordance with the kind of the image recording medium.
In the system, the parameter control section includes a temperature control section controlling temperature of the squeezing member with respect to the recording drum based on the conversion table in accordance with the kind of the image recording medium.
In the system, the characteristics of the image recording mediums may be sensitivity characteristics of each of the recording mediums.